function fab(n){
    return n < 3 ? 1 : fab(n-1)+fab(n-2)
}
var onmessage = function(event){
    var v = event.data
    console.log('分线程接收到的主线程发送的数据:' + v)
    postMessage(fab(v))
    console.log('分线程向主线程返回数据:' + fab(v))
}

var b = new Object()
var a = null
var c
console.log(typeof b, typeof a)
console.log(b instanceof Object, c === undefined)